Strap guide



M. B. HALL STRAP GUIDE Sept. 4, 1962 4 SheetsSheet 1 Filed NOV. 29, 1960p 1962 M. B. HALL 3,052,178

STRAP GUIDE Filed NOV. 29, 1960 4 Sheets-Sheet 2 INVENTOR.

WMiQdJMJA W@Q%wu Sept. 4, 1962 M. B. HALL 3,052,178

STRAP GUIDE 4 Sheets-Sheet 3 Filed Nov. 29, 1960 INVENTOR.

M. B. HALL STRAP GUIDE Sept. 4, 1962 4 Sheets-Sheet 4 Filed Nov. 29,1960 3,052,178 STRAP GUIDE Marchand B. Hail, Olympia Fields, Ill,assignor to Acme Steel Company, Qhicago, Ill, a corporation of IllinoisFiled Nov. 29, 1960, Ser. No. 72,499 12 Claims. (Cl. 100-25) (Thisinvention relates to the art of strap guide tracks and particularly toone which enhances the use of a conventional type track wherein a lengthof strapping is guided around an object to be strapped prior totensioning of the strap on the object and connecting together the endsof the strap length.

When strapping objects at the present time, it is common to secure theobject or load by means of the straps to an underlying support palletwhich provides a convenient means on which the object can be supportedduring subsequent handling, storage and shipment. On certain typepallets where the pallet consists of a platform supported by post typelegs or longitudinal runners, little difficulty is encountered inproperly encircling the straps around the pallet to secure it to theload or object which it supports. However, when a double faced pallet isused, viz., one which consists of two parallel faces or sheets spacedapart by means of spacers or legs, it is desirable that the strapsextend in the space between the two faces of the pallet so that theupper face only is actually strapped to the object. The obvious way ofthreading the straps through this space is manually by passing theleading strap end from one side of the pallet to the other. This is atime consuming operation and does not lend itself to high enoughproduction to keep abreast of the swiftness of the ordinary high speedassembly line.

It is, therefore, the principal object of this invention to provide animproved strap guide track having novel retractable means which can beextended into the space between the two faces of a double faced palletwhere the means provides a guide for facilitating the passage of a straplength endwise through the space so that a strap can be quickly andeasily encircled around an object supported on the pallet.

In order to accomplish this object, it is another object to provide anovel type retractable guide which can be first inserted into the spaceof the pallet when the strap is to be encircled on the object, and thenretracted after encircling of the strap has been completed.

The form of the retractable means of this invention is a metal slatwhich is bowed into a transverse concavoconvex cross section to firstprovide rigidity for proper support of a strap and secondly provide atrough into which the strap can be properly guided. Also, for spaceconservation, the metal slat is retracted by rolling it up into a coilwhich can be unwound when the metal slat or guide is extended.

It is another object of the invention to provide a retractable guide asdescribed which is powered by a suitable motor having an improvedcontrol means for arresting the movement of the guide at the ends ofboth its extended and retracted positions. The improved control means isadvantageous for accurately predetermining both the extended andretracted positions.

In a copending application entitled Strap Guide of Alvin L. Winkler,Serial Number 27,556, filed May 29, 1960, now Patent No. 2,985,098,patented on May 23, 1961 there is described and shown a retractablemetal slat strap guide of the same type as shown and described in thisapplication. However, in that application the strap guide is bent arounda pulley and raised vertically when retracted with the disadvantage thatmuch space is used for the vertical support required. The invention ofBfiiifili Patented Sept. 4, 1962 ice this application is an improvementover the invention of that application, primarily because of itscompactness which facilitates its use in the many places where space isa problem.

Other objects and advantages of the invention should become apparentupon reference to the accompanying drawings, in which FIG. 1 shows apartially cutaway and partial sectional side elevation of strappingapparatus embodying the invention;

FIG. 2 is a sectional view along the line 22 of FIG. 1 showing therelationship of the strap guide path between the faces of a pallet;

FIG. 3 shows a partial sectional and simplified side elevation view ofthe belt driving means for the retractable guide;

FIG. 4 shows an enlarged view of the lower right hand portion of FIG. 1;

FIG. 5 shows a top plan view of the strap guide unit of FIG. 4;

FIG. 6 shows a sectional view along the line 66 of FIG. 4;

FIG. 7 shows a sectional view along the line 77 of FIG. 4;

FIG, 8 shows a sectional FIG. 4;

FIG. 9 shows an enlarged top plan view of the power control means;

FIG. 10 shows an enlarged front view of the same power control means ofFIG. 9;

FIG. 11 shows an enlarged end view of the power control means of FIG. 9;

FIG. 12 shows a still further enlarged sectional view of certainportions of the power control means for illustrative purposes;

FIG. 13 shows a sectional view along the line 13-13 of FIG. 1 andparticularly shows the cross sectional shape of the form of strap guideto be used with the invention; and

FIG. 14 shows a simplified schematic wiring diagram of the electricalcontrol circuit for controlling the power operation of the invention.

The particular embodiment of the invention as shown is mounted on aframe 1 which ordinarily rests on the floor where the invention is to beused. The frame 1 is provided with a conveyor 2 consisting of aplurality of spaced parallel positioned rollers 3 journaled to the frameI. These rollers 3 are freely journaled so that an object can be rolledacross their upper surfaces with a minimum of effort. Secured to therear of the rollers in a vertical direction from the frame 1 is anupright member 4 whose upper end is provided with a horizontal arm 5extending in cantilever from it and directly over the region of theconveyor rollers 3. Secured by means of L-shaped clips 6 on either sideof the upright member 4 and the horizontal member 5 is a flexible strapguide tube 7. The clips are held in place on the members 4- and 5 bymeans of screws 8 as best shown in FIG. 13. The guide tube '7 terminatesat its upper end 9 slightly beyond the end of the horizontal member 5while its lower end 10 terminates approximately slightly above the levelof the rollers 3 and in the vicinity of their rear ends.

The guide tube "7 is preferably manufactured from flexible plastic orrubber and can be extruded into the cross sectional shape shown in FIG.13. Although this plastic tube type guide is shown, there are many otherways of manufacturing guide tubes to perform the same general functionand the particular structure shown forms no part of the invention perse, as hereinafter claimed.

Since plastic or rubber ordinarily is soft enough that it can create asnag problem with the leading end of a view along the line 8 -8 of 2)strap fed through a guide tube made from it, a backing strip 11 ofstainless steel or other smooth metal is positioned through the tube forits entire length. Its ends 11a and 1112 are cur-led around the ends 9and 10 of the tube in order to retain it positioned in the tube.

Extending parallel to the horizontal arm is another arm 12 Which is alsosupported in cantilever from the upright member 4-. it is supplied witha motor 13 having a feed wheel 14 mounted on its shaft. Directly belowthe feed wheel 14 is an idler wheel 15 mounted on another shaft. Theidler wheel 15 is positioned. closely enough to the feed wheel 14 sothat when strap 16 is positioned be-. tween the two Wheels 14 and 15 andthe feed wheel 14 is rotated, the strap 16 is caused to movelongitudinally between the wheels in a direction dependent upon thedirection of rotation of the feed wheel 14. The idler wheel 15 isnecessarily free wheeling in either direction. For convenience, theidler wheel 15 can be made retractable away from the feed wheel 14 topermit easy removal of the strap 16 when necessary but this forms nopart of the invention.

The guide tube 7 is provided with an enlarged base 7a which is theportion held by the clips 6'. Attached to the base portion 7a are twoflexible arms 7b and 70 which in their normal positions abut at theirends along a line of contact 7d. In these positions, the arms 7b and 70form a circle having a longitudinal circular opening 7e extendingentirely through the guide tube 7 from one end to the other. When theguide tube is used for guiding strap around an object, the strap 16 ispassed entirely through the guide tube '7. When it is necessary toremove the strap from the guide tube 7 the strap is pulled way from theguide tube and the pulling force causes the strap 16 to cam against thearms 7 b and 7c and spread them apart to the positions as indicated inphantom lines in FIG. 6 where an opening large enough for the strap 16to be removed is created. After the strap is removed, the naturalresiliency of the arm 7b and 7c causes them to return to their initialpositions. Since the arms 7b and 7c are flexible for their entirelength, the strap 16 can be stripped from the tube 7 progressively fromend to end.

At the rear of the frame 1 is mounted another frame 17 which consists oftwo vertically spaced base plates 17a and 17a which are secured to thelower edges of two large side plates 18 and 19 which extend upwardlyabove the base plates 17a and 17a. These two side plates 18 and 19support all of the mechanism related to the retractable strap guide andcan be referred to as the retractable strap guide unit.

Journaled on spaced bearings 21? and 21 in the side plates 18 and 19 isa drum shaft 22 on which is secured, by means of a set screw 23, a drum24. Around this drum is ordinarily wrapped the retractable strap guide25. This strap guide 25 is, in its extended position, in the form of alarge slathaving a concave-convex cross sectional shape. The slat orguide is preferably made of thin steel strip formed with the requisitetransverse curvature, but can probably be manufactured s'atisfac torilyfrom plastic or other flexible material. The inner end of the guide 25is bifurcated to have two spaced ears 25a and 25b connected to two loops26 which are fitted over opposite ends of a pin 27 secured through anaperture 28 in the drum 24. By proper guiding of the guide 25 as thedrum 24 is rotated, the guide 25 is Wound, layer upon layer, onto thedrum 24, and the pin 27 maintains the guide connected to the drum 24.

As viewed in FIGS. 1, 4 and 5, the guide 25 ordinarily projects beyondthe drum 24 with its free end 29 adjacent to the end of the guide tube7. When a pallet 46 supporting -a load 46a is properly positioned on theconveyor 2 at the strapping station adjacent to the guide tube 7, inorder to guide the strap 16 in the space 48 between the two parallelfaces 46b and 460 of the pallet 46, the guide 25 is unwrapped from thedrum 24 by rotating the drum in -a clockwise direction so that the end29 of the guide is projected into the space 48 which is in the end ofthe shaft which is there threaded.

path of the strap 16 leading from the lower end 10 of the guide tube 7.With the strap guide positioned in this manner, the strap 16 as it isfedforward in the direction of the arrow 49, is guided through the opening48 of the pallet so that its leading end 16a emerges beyond the oppositeside of the pallet. After this threading operation through the pallet iscompleted, the two ends of the strap 16a and 1617 are tensioned towithdraw the strap 16 out of the guide tube 7 and tightly around thesides of the package 46a supported on the pallet. Conventional strappingtools can then be used to tension the strap tightly, secure the ends16:1 and 16b together and sever the secured strap loop on the packagefrom the supply end 16b which can still be connected to a source ofstrap supply.

In order to properly guide the strap guide 25 as it is either extendedor retracted, its marginal edges are guided in four grooved edge rolls3d, 31, 32 and 33 which are each journaled on a bracket 34 secured tothe side plates 18 and 19. These guide rolls 30 to 33 guide the strapguide 25 in a horizontal direction, but could just as well beconditioned to guide the strap guide in an angular direction if such acondition would be required, as in a situation where the conveyor may besloped.

There are two other guide rolls 35 and 36 which are each journaled in abracket 37 and these guide rolls 35 and 36 are positioned to contact theedges of the strap guide 25 in a portion of the periphery of the drumwhere the layers of the strap guide 25 build up as it is wrapped ontothe drum 24. The purpose of these guides is to keep the wrappedconvolutions of the strap guide in alignment with each other. Inaddition to the guide means just mentioned for the strap guide, it isnecessary to provide a driving means to cause the strap guide 25 to beeither extended or retracted. The means for accom-. plishing this is aflexible belt 38 wrapped around the coiled strap guide 25, as especiallyviewed in FIG. 3. The belt 33 is wrapped around about three-fourths ofthe circumference of the wrapped strap guide and is directed around fourbelt pulleys 39, 4t), 41 and 42, to maintain the belt in a closed looppath. All four of these pulleys are suitably journaled on four shafts43, 4d, 45 and 46 mounted between the side plates 18 and 19. Each of theshafts 43 to 46 are provided with spacer sleeves 47 on both sides oftheir respective pulleys so as to maintain the pulleys centrally located'on the shafts.

Although the pulleys li, 41 and 4-2 are all idlers, the pulley 39 isdriven. Its shaft 43 is journaled in bearings 47 and 4S. Adjacent eachbearing is a spacer sleeve 49 which abuts both the inner race of abearing 47 or 48 and the inner race of a more centrally positionedbearing 59 or 51, these bearings 59 and 51 being on immediately oppositesides of the pulley 39. At one end of the shaft 43 it is provided with aspring 52 mounted between the bearing 4% and a double nut 53 which issecured on the The spring 52 reacts between the inner race of thebearing 48 and the nut 53 to urge the shaft 43 in a direction toward theright, as viewed in FIG. 7. On the other end of the shaft 43 is secureda pulley 54 and between it and the inner race of bearing 47 are twospacer sleeves 55 and 56. The effect of urging the shaft 43 to the rightis to draw all of the sleeves in the inner races of the bearings towardeach other and thereby clamp the inner races of bearings 54) and 51across the pulley 39. This clamping action creates a frictional drivecondition between the shaft 43 and the pulley 39 so that, upon rotationof the pulley 54, the pulley 39 is rotated. The purpose of thisfrictional drive is to provide a safety overload feature which permitsslippage of the pulley 39 or its driving shaft 43 in case of jamming.

From this driving arrangement shown it should be evident that rotationof the pulley 39 in a clockwise direction causes the strap guide 25 tobe retracted and wound about the drum 24, while rotation of the pulley3% in the opposite direction causes the strap guide 25 to be extended asthe strap guide is unwound from the pulley 24.

The means for driving the pulley 54 which drives the pulley 39 is bymeans of another belt 57 which is driven from the pulley 58 of a motor59. This motor 59 is mounted between the top edges of the side plates 18and 19 and is preferably an electric motor, although other types can beused.

Although it is not essential, it is desirable to have a control systemfor the motor which permits predetermined actuation of it so that theretractable guide is either extended or retracted a deliberate amounteach time it is actuated without requiring that the operator guess whento energize and tie-energize the motor.

The control system for the motor is particularly shown in FIGS. 6, 9,10, 11 and 12. The end of shaft 22 which passes through bearing 20 isthreaded and projects quite far beyond the side plate 18 in which thebearing 20 is mounted. This threaded end 22a of the shaft 22 is firstprovided with two threaded nuts 60 and 61 which can be locked togetherin a fixed position on the shaft 22 by means of two lock washers 62. Thenut 61 is provided internally with the inner end of a helical spring 63which is welded or soldered to it. The spring 63 acts as the threads ofthe nut 61 and engages the threads on the end 22a of the shaft 22. Thenut 60 is internally threaded to directly engage the threads of theshaft end 2211. With the spring 63 securely bonded to the nut 61 asdescribed, rotation of the nut 61 on the threads of the shaft end 22acauses rotation of the spring 63 with it. Beyond the free end 63a of thespring 63 is mounted an inverted U-shaped bracket 64 by means of aninternally threaded circular nut 65. The circular nut 65 has an enlargedcenter portion having annular end walls 65a. guided against the insidewalls of the bracket 64 and it also has reduced diameter ends 65b and650 which project into round openings 66 and 67 in the side walls of thebracket 64. Through apertures in the side walls of the bracket 64 isalso mounted a screw 68 which is held in place by means of a nut 69 atits end. The effect of tightening of the nut 69 on the screw 68 is todraw the two side walls of the bracket 64 together and thereby clamp thecircular nut 65 fixed relative to the bracket 64. When rotation of thecircular nut 65 is required for adjustment, the nut 65 is loosened sothat the pressure of the side plates of the bracket 64 is relievedagainst the ends of the circular nut 65, at which time the circular nutis free to be rotated relative to the bracket 64. During this rotationalmovement, it is urged one way or another on the shaft 22 because of itsthreaded engagement with it. The purpose of this adjustment of thecircular nut 65 is hereinafter described.

Adjacent to the extreme end of the shaft end 22a are two more nuts 70and 71. The nut 71 is similar to 60 and is internally threaded todirectly engage the threads of the shaft 22 and it is a locking nut fornut 70. The nut 70 is similar to nut 61 and is provided with a helicalspring 72 which is soldered r welded to it in the same manner. Thespring 72 acts as the internal thread for the nut 70 on the threads ofthe shaft 22. Rotation of the nut 70 causes rotation of the spring 72and causes the spring to move one way or the other longitudinally on theshaft, depending upon which direction the nut 70 is rotated.

On the outer surfaces of the side walls of the bracket 64 are mountedtwo switches 73 and 74. These switches have actuating arms 73a and 7 4awhich extend transversely over the shaft 22. These switches 73 and 74are secured by means of screws 75 to the side walls of the bracket 64.The bracket 64 is provided with a pin 76 which has its inner end securedto the side plate 18 while its outer end is secured through the sidewalls of the bracket 64. This pin maintains the bracket 64 in a fixedangular relationship to the shaft 22.

With the switch actuating arm-s 73a and 74a positioned laterally acrossthe shaft 22 in the path of the springs 63 and 72, as the bracket 64 ismoved along the shaft 22 in one direction or another, the arms 73a and74a. are actuated alternately by contact with the ends 63a and 72a ofthe two springs.

In actual operation, the switches are used to arrest the operation ofthe driving motor 59 upon both retraction and extension of the strapguide 25. In FIG. 9, it may be assumed that the positions of the switcharms 73a and 74a are as they would be when the strap guide is extendedinto the space 48 between the pallet faces 46b and 46c. In this case thearm 74a is pivoted upwardly onto the spring end 72a. In this position ofthe arm 74a, the contacts of switch 74 are open. At this same time, thearm 73a is off of the spring end 63a and resting upon the threads of theshaft 22. In this position of the arm 73a, the contacts of the switch 73are closed. When it is desired to retract the strap guide 25, anotherswitch in series with switch 73 is closed and this energizes the motor59 to cause rotation of the coil of strap guide 25 in a direction tocause it to be further wrapped onto the drum 24. As the drum 24 isrotated in this manner, its shaft 22 is likewise rotated and this shaftsthreaded engagement with the circular nut 65 causes the bracket 64 to bemoved toward the left as viewed in FIG. 9. Movement of the bracket 64 tothe left causes the switches 73 and 74 to likewise be moved to the leftrelative to the shaft 22 so that the switch arm 74a falls off of the end72a of the spring and onto the threaded portions of the shaft 22 toclose the contacts of the switch 74. Shortly thereafter, when thebracket 64 has moved far enough, the switch arm 73a contacts the end 63aof the spring 63 to cause the arm 73a to be raised to open the contactsof the switch 73. Closing of the contacts of switch 7 4 prepares thecircuit for again causing the strap guide to be extended, While openingof the contacts of switch 73 breaks the circuit with the electric motor59 and thereby arrests the operation to arrest the retraction of thestrap guide 25. In this manner, by having the springs 63 and 72 properlyspaced, it is possible to accurately determine the limits of movementduring extension and retraction of the strap guide 25.

The fit of the pin 76 through the walls of the bracket 64 is looseenough that the bracket 64 is free to move over it as the shaft 22 isrotated to cause such movement.

FIG. 12 indicates schematically the reason for the adjustment of thecircular nut 65 relative to the bracket 64. If the initial angularposition of where the start of the internal thread of the circular nutis not proper, it is possible that the switch arm 74a will possiblyfirst contact the end 72a of the spring 72 at a position indicated byphantom lines in that view. In that position it is possible thatinsufiicient movement of the switch arm 74a will not have occurred tocompletely actuate the switch. If this is true, the nut 69 is loosenedand the circular nut 65 is adjusted until arm 74a is upon the spring end72a as shown in solid outline in FIG. 12.

By referring to FIG. 14, the entire electrical operation of the controlsinvolving switches 73 and 74 can be described. In FIG. 14, a suitablesupply voltage is applied between wires 77 and 78. Upon closing of amaster switch 79 connected to these wires 77 and 78, the voltage iscarried between conductors 80 and '81. At this time, none of theelectrical components are energized. However, switch 73 is closedbecause its switch arm 73a is off of the end 63a of the spring 63 andswitch 74 is open because its arm 74a is on the spring end 72a. Also, aspreviously described, the guide 25 is extended at this time. In order tocause reversal or retraction of the guide 25, the reverse switch 82 isclosed manually. This applies voltage from conductors 80 and 81 across arelay solenoid 83 by way of closed switch 73. This energizes solenoid 83to cause the solenoid contact switches 83a and 83b to be closed. Closingof contact switch 83b maintains solenoid 83 energized after the reverseswitch 82 is spring returned after release by the operator. Contactswitch 83a energizes the electric motor 59 through conductors 84 and 85so that the motor 59 rotates in a direction corresponding to thatrequired for retraction of the guide. As the guide 25 is retracted, thebracket 64 is moved to the left, as viewed in FIG. 9, because ofrotation of the shaft 22 during this time. The movement of the bracket64 correspondingly moves the switches 73 and 74 to the left with it. Ata predetermined time, determined by the spacing between the spring ends63a and 72a, the switch arm 73a rides up on to the spring end 63a tocause switch 73 to be opened. During the initial movement of the bracket64, however, switch 74a is closed as the spring arm 74a falls off of thespring end 72a. Opening of switch 73 de-energizes relay solenoid 83 toallow the spring return of its contact switches 83a and 83b to open.Opening of switch contact 8311 sets up the circuit for the next cycle ofoperation while opening of switch contact 83a tie-energizes the motor 59and arrests its motion. When the motion of the motor 59 has come torest, the guide 25 will have also been arrested in its movement so thatit is completely retracted.

When it is again desired to extend the guide, a forward switch 86 isclosed manually to energize a relay solenoid 87 through the closedswitch 74. Energization of the solenoid 87 causes its switch contacts87a and 87b to be closed. 87b is a holding contact for solenoid 87 tomaintain it energized after the actuating button for the forward switch86 is spring returned upon manual release. Closing of switch contact 87aenergizes the motor 59 through conductors 88 and 85. Since the motor 59is a reversing type motor wherein its direction of rotation isdetermined by whether it is energized through conductors 84 or 88,energizing this motor 59' through the conducter 88 causes it to berotated in a direction to cause the guide 25 to be extended. When theshaft 22 rotates sufliciently, the bracket 64 will have movedsufliciently to the right that the switch arm 73a will have moved ofl ofthe spring end 6311 to close switch 73 and the switch arm 74a will havemoved onto the spring end 72a so that the switch 74 is again opened. Theparts are then all in the positions as shown in FIGS. 9 and in readinessfor the cycle to be repeated.

Although a control system has been provided for predetermining theextension and retraction of the strap guide automatically, it should beapparent that the operator could control the motor 59 by having theforward and reverse switches 86 and 82 in series with the conductors 88and 84 respectively so that reversal of the motor and its stoppage andstarting can be controlled directly by manual means. This is not toodesirable, however, since much greater skill is required of the operatorthan is thought reasonable. Nevertheless, the main essence of theinvention, viz., a roll up type retractable strap guide is not alteredwhether the operation is by automatic control means or entirely bymanual means. In fact, it is also considered possible, although not aspractical, to provide merely a hand crank on the drum shaft 22 whichcould accomplish the same purpose as the motor.

Although only a single embodiment of the invention has been shown anddescribed, it should be understood that the invention can be made inmany different ways without departing from the true scope of theinvention, as defined by the appended claims.

I claim:

1. The combination in strapping apparatus, of support means forsupporting a pallet of a type having a horizontal opening extendingthrough it, a retractable sheet metal strap guide, and means for bothretracting and extending the retractable stra guide through thehorizontal opening of the pallet where it can guide a strap fed endwisethrough the opening, said strap guide being of concavo-convex crosssection to impart rigidity to it so that it is self-supporting incantilever and its concave side facing upward as a trough for guiding astrap fed endwise over it when the guide is in its extended position,the sheet metal from which the strap guide is made being flexible enoughto allow the guide to be 'bent to follow a nonrectilinear path as theguide is extended and retracted, the sheet metal of the guide also beingresilient enough to cause the guide to retain its concavo-convex crosssection along its straight path portions, said means for re tracting andextending the retractable strap guide comprising a hub around which thestrap guide is wrapped.

2. The combination in strapping apparatus, of support means forsupporting a pallet of a type having a horizontal opening extendingthrough it, a retractable sheet metal strap guide, and actuating meansfor retracting and extending the retractable strap guide through thehorizontal opening of the pallet where it can guide a strap fed endwisethrough the opening, said strap guide being of concavo-convex crosssection to impart rigidity to it so that it is self-supporting incantilever and flexible enough to allow it to be bent into a coil, withthe concave-convex cross section flattened and resilient enough toreturn to its original concavo-convex cross section when unwound from acoil shape, said actuating means for retracting and extending theretractable strap guide comprising coiling means around which the strapguide is wrapped into a coil.

3. The combination in strapping apparatus, of support means forsupporting a pallet of a type having a horizontal opening extendingthrough it, a retractable strap guide, and actuating means forretracting and extending the strap guide through the horizontal openingof the pallet where it can guide a strap fed endwise through theopening, said strap guide being of concave-convex cross section toimpart rigidity to it so that it is self-supporting in cantilever andflexible enough to allow it to be bent into a coil with theconcavoconvex cross section flattened and resilient enough to return itto its original concavoconvex cross section when unwound from a coilshape, said actuating means for retracting and extending the retractablestrap guide including coiling means around which the strap guide iswrapped into a coil.

4. The combination in strapping apparatus according to claim 2characterized by, and drive means for driving said coiling means forcausing said retractable strap guide to be selectively coiled oruncoiled around said coiling means.

5. The combination in strapping apparatus according to claim 3characterized by, and drive means for driving said coiling means forcausing said retractable stra guide to be selectively coiled or uncoiledaround said coiling means.

6. The combination in strapping apparatus, of support means forsupporting a pallet of a type having a horizontal opening extendingthrough it, a retractable strap guide, and actuating means forretracting and extending the strap guide through the horizontal openingof the pallet where it can guide a strap fed endwise through theopening, said strap guide being of concave-convex cross section toimpart rigidity to it so that it is self-supporting in cantilever andflexible enough to allow it to be bent into a coil with theconcavo-convex cross section flattened and resilient enough to return itto its original concavo-convex cross section when unwound from a coilshape, hub means around which the retractable strap guide can he woundinto a coil, and drive means engaging the strap guide to drive it in onedirection or the other in order to alternatively unwind it from and ontothe hub means for extending and retracting it.

7. The combination in strapping apparatus according to claim 6characterized by, said drive means having a driving belt engaging thestra guide in a region where it is wound into a coil, said belt drivenby a prime mover.

8. The combination in strapping apparatus according to claim 6characterized by, said hub means having stop means thereon forcontrolling the amount of extension and retraction of the retractablestrap guide.

9. The combination in strapping apparatus according to claim 6characterized by, said drive means including an electric motor as aprime mover for it, said hub means being mounted on a shaft which isrotated with said hub means as the retractable strap guide is extendedand retracted, said shaft being threaded to threadedly engage a switchcarrier which is moved longitudinally along said shaft as the shaftrotates, stop means being provided on said shaft for actuating switchesmounted on said switch carrier, said switches being in an electricalcircuit with said motor so that their actuation controls the actuationof the motor to thereby control the extension and retraction strokes ofthe retractable strap guide.

10 The combination in strapping apparatus according to claim 6characterized by, said drive means including an electric motor as aprime mover for it, said hub means being mounted on a shaft which isrotated with said hub means as the retractable strap guide is extendedand retracted, said shaft being threaded to threadedly engage a switchcarrier which is moved longitudinally along said shaft as the shaftrotates, stop means being provided on said shaft for actuating switchesmounted on said switch carrier, said switches being in an electricalcircuit with said motor so that their actuation controls the actuationof the motor to thereby control the extension and retraction strokes ofthe retractable strap guide, said stop means being the ends of spacedapart helical springs wound onto said threaded shaft.

11. The combination in strapping apparatus according to claim 6characterized by, said drive means having a driving belt engaging thestrap guide in a region where it is wound into a coil and said beltbeing driven by an elec- 10 tric motor, said hub means having electricalswitch means connected thereto for controlling the actuation of saidelectric motor and thereby control the amount of extension andretraction of the retractable strap guide.

12. The combination in strapping apparatus according to claim 6characterized by, said drive means including an electric motor as aprime mover for it, said hub means being mounted on a shaft which isrotated with said hub means as the retractable strap guide is extendedand retracted, said shaft being threaded to threadedly engage a switchcarrier which is moved longitudinally along said shaft as the shaftrotates, stop means being provided on said shaft for actuating switchesmounted on said switch carrier, said switches being in an electricalcircuit with said motor so that their actuation controls the actuationof the motor to thereby control the extension and retraction strokes ofthe retractable strap guide, said stop means being the ends of spacedapart helical springs wound onto said threaded shaft, said helicalsprings being threadedly adjustable along said shaft in order to adjustthe end positions of the retractable strap guide when it is extended andretracted.

References flirted in the file of this patent UNITED STATES PATENTS2,236,136 Gorman Mar. 25, 1941 2,725,436 Crocker Nov. 29, 1955 2,780,986Ritenour Feb. 12, 1957 2,831,422 Black et al Apr. 22, 1958

